A tracked work machine, such as a track-type tractor or an excavator, is typically supported and propelled by a pair of undercarriage assemblies. Each of the pair of undercarriage assemblies includes an endless track chain having a number of interconnected articulating components or links. Each undercarriage assembly typically also includes a drive wheel or sprocket and one or more idler wheels. During operation, the track chain advances around the drive wheel and the one or more idler wheels.
Generally, it is desirable to have the track chain relatively taut while digging or performing any other type of work operation in order to prevent a machine from rolling back and forth within the interior of the track chain. This may take place due to recoil forces generated during performance of the work operation. To create tension on the track chain, the hydraulic cylinder or the coiled spring of the tension adjustment mechanism urges the idler wheel away from the drive wheel, increasing the dimension of the undercarriage assembly which the track chain must encircle.
In contrast, it is also desirable to have the track chain relatively loose during advancement or travel of a track-type tractor. In order to reduce tension in the track chain, the hydraulic cylinder or coiled spring of the tension adjustment mechanism allows the idler wheel to move toward the drive wheel.
The tension adjustment mechanism also provides a recoil functionality in the track chain, accommodating temporary forces on the track such as when an obstacle, for example a rock, is ingested between the track and the wheels during advancement of the track-type tractor. In these instances, the idler wheel may recoil towards the drive wheel in order to accommodate the extra length the track must encircle to accommodate the rock without breaking.
Current designs make use of bearing blocks to support the hydraulic cylinder. The bearing blocks may include wear strips along which the hydraulic cylinder may slide. The wear strips may require frequent maintenance and/or replacement, leading to increased machine downtime and associated costs.
U.S. Pat. No. 8,011,740 (hereinafter referred to as '740 reference) describes a track type tractor including a modular track roller frame made up of easily assembled sub-components. Among these sub-components are an idler recoil assembly that may slide into, and then fastens to a housing as a unit to create a track roller frame assembly. The idler recoil assembly includes a gas spring telescoping section and a length adjustment telescoping section located between a housing contact end and a yoke contact end. However, the '740 reference does not describe a maintenance free design of the idler recoil assembly.
Hence, there is a need for an improved recoil mechanism associated with the undercarriage assembly.